1. Technical Field
The present application relates to armatures and commutators for electric motors. In particular, the application is directed to a combined armature and commutator wherein the armature is structurally supported for rotation by the commutator.
2. Description of Related Art
Electric motors and their construction are generally well known. U.S. Pat. No. 5,434,463 relates to a representative direct current motor which utilizes a commutator in combination with crescent shaped brushes. The commutator is positioned within a core-type armature. The disclosure of U.S. Pat. No. 5,434,463 is incorporated herein by reference.
Commonly assigned U.S. Pat. No. 4,910,790 relates to a two speed motor which incorporates first and second respective commutators and brush set to accommodate each speed of the motor. The disclosure of U.S. Pat. No. 4,910,790 is incorporated herein by reference.
U.S. Pat. No. 5,095,611 relates to a method of assembling an electric motor to eliminate a separate end play adjustment wherein permanent magnets act on the armature laminations to urge the motor shaft in one direction so that the entire end play appears at only one end of the shaft. The disclosure of U.S. Pat. No. 5,095,611 is incorporated herein by reference.
Commonly assigned, concurrently filed U.S. patent application entitled Commutators for Electric Motors and Method of Manufacturing Same, the disclosure of which is incorporated herein by reference, is directed to a novel method of manufacturing commutators which eliminates costly manufacturing steps and loss of material. Commonly assigned, concurrently filed application entitled Commutator for Two Speed Electric Motor and Motor Incorporating Same, the disclosure which is incorporated herein by reference, is directed to a novel commutator for use in two speed motors, which minimizes the axial space utilized by the commutator.
In electric motors the armature and commutator are generally spaced apart from each other axially along the motor shaft and wired in a manner to function as part of the motor. The armature is generally mounted to the motor shaft for rotation within a magnetic field created by permanent magnets. The armature is usually rotatably supported on the shaft by a plurality of radial spoke-like members. As is well known, the armature generally includes a core comprised of a stack of laminations formed of a ferromagnetically compatible material such as steel, and secured together to form the core. Generally the steel laminations have a central opening and selected laminations have radial spoke-like members. The laminations are spaced in a prearranged manner such that the spoke-like members may be used to support the entire stack of laminations on a bearing mounted rotor shaft. The core of laminations is wrapped with electrically conductive armature wires to produce the electric field required to produce rotary motion of the armature on the bearing mounted rotor shaft. Alternatively, the core may be made of a solid ferromagnetic material.
The commutator can be of various types. One type is in the form of a disk-like support member carrying commutator segments on one surface of the disk-like support member. Another type is the barrel-type commutator which has a cylindrical structure and carries commutator segments on the outer cylindrical surface and is mounted on the rotor shaft adjacent to, and generally independently of the armature. In either arrangement the armature and the commutator utilize separate spaces along the axial length of the shaft and therefore cause the motor to be longer in length than would otherwise be desirable.
U.S. Pat. No. 4,286,375 relates to a method of manufacturing a coreless armature wherein the armature comprises a cylindrically wound insulation coated coil as a main armature body. A disk-shaped commutator carrying plate member is positioned within the insulation-coated coil body and pressure is applied in all radial inward directions such that a compressive force is applied to the outer periphery of the coil body to cause the coil windings to partly bulge into ring-shaped spaces surrounding the commutator carrying member. The method of U.S. Pat. No. 4,286,375 relates to manufacturing a commutator carrying member within a coreless armature. The method however, does not contemplate a core-type armature which utilizes a core comprised of a plurality of ferromagnetic plates secured together to form the core and having armature windings wound therearound. The present invention relates to a combined armature and commutator which structurally supports the armature for rotation on the rotor shaft of electric motors of the type which utilize a core-type armature.